CN113999424A - Preparation method of polypropylene foam material with controllable internal pressure - Google Patents
Preparation method of polypropylene foam material with controllable internal pressure Download PDFInfo
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- CN113999424A CN113999424A CN202110464701.0A CN202110464701A CN113999424A CN 113999424 A CN113999424 A CN 113999424A CN 202110464701 A CN202110464701 A CN 202110464701A CN 113999424 A CN113999424 A CN 113999424A
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- 239000004743 Polypropylene Substances 0.000 title claims abstract description 151
- -1 polypropylene Polymers 0.000 title claims abstract description 151
- 229920001155 polypropylene Polymers 0.000 title claims abstract description 151
- 238000002360 preparation method Methods 0.000 title claims abstract description 14
- 239000006261 foam material Substances 0.000 title claims abstract description 7
- 238000005187 foaming Methods 0.000 claims abstract description 94
- 239000011324 bead Substances 0.000 claims abstract description 61
- 238000007334 copolymerization reaction Methods 0.000 claims abstract description 49
- 239000004594 Masterbatch (MB) Substances 0.000 claims abstract description 42
- 239000002667 nucleating agent Substances 0.000 claims abstract description 33
- 238000000034 method Methods 0.000 claims abstract description 31
- 229920005604 random copolymer Polymers 0.000 claims abstract description 29
- 238000000465 moulding Methods 0.000 claims abstract description 25
- 238000003825 pressing Methods 0.000 claims abstract description 18
- 238000001125 extrusion Methods 0.000 claims abstract description 17
- 239000002994 raw material Substances 0.000 claims abstract description 16
- 238000006243 chemical reaction Methods 0.000 claims abstract description 15
- 239000012792 core layer Substances 0.000 claims abstract description 10
- 239000010410 layer Substances 0.000 claims abstract description 10
- 238000005469 granulation Methods 0.000 claims abstract description 9
- 230000003179 granulation Effects 0.000 claims abstract description 9
- 239000006260 foam Substances 0.000 claims abstract 2
- 239000004677 Nylon Substances 0.000 claims description 24
- 229920001778 nylon Polymers 0.000 claims description 24
- 238000002844 melting Methods 0.000 claims description 20
- 230000008018 melting Effects 0.000 claims description 20
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 16
- 239000000155 melt Substances 0.000 claims description 16
- 239000000463 material Substances 0.000 claims description 12
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 8
- 239000001569 carbon dioxide Substances 0.000 claims description 8
- 239000004088 foaming agent Substances 0.000 claims description 8
- 238000012360 testing method Methods 0.000 claims description 7
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 6
- 238000005303 weighing Methods 0.000 claims description 6
- BIKXLKXABVUSMH-UHFFFAOYSA-N trizinc;diborate Chemical compound [Zn+2].[Zn+2].[Zn+2].[O-]B([O-])[O-].[O-]B([O-])[O-] BIKXLKXABVUSMH-UHFFFAOYSA-N 0.000 claims description 5
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 4
- 229910000019 calcium carbonate Inorganic materials 0.000 claims description 3
- FPAFDBFIGPHWGO-UHFFFAOYSA-N dioxosilane;oxomagnesium;hydrate Chemical compound O.[Mg]=O.[Mg]=O.[Mg]=O.O=[Si]=O.O=[Si]=O.O=[Si]=O.O=[Si]=O FPAFDBFIGPHWGO-UHFFFAOYSA-N 0.000 claims description 3
- 238000007789 sealing Methods 0.000 claims description 3
- 235000012239 silicon dioxide Nutrition 0.000 claims description 3
- 239000000377 silicon dioxide Substances 0.000 claims description 3
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 2
- 239000004408 titanium dioxide Substances 0.000 claims description 2
- 230000001788 irregular Effects 0.000 description 5
- 238000001816 cooling Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000007493 shaping process Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 238000007766 curtain coating Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000007717 exclusion Effects 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000010345 tape casting Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/04—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent
- C08J9/12—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a physical blowing agent
- C08J9/122—Hydrogen, oxygen, CO2, nitrogen or noble gases
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B9/00—Making granules
- B29B9/02—Making granules by dividing preformed material
- B29B9/06—Making granules by dividing preformed material in the form of filamentary material, e.g. combined with extrusion
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
- B29C44/34—Auxiliary operations
- B29C44/60—Measuring, controlling or regulating
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/0061—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof characterized by the use of several polymeric components
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/22—After-treatment of expandable particles; Forming foamed products
- C08J9/228—Forming foamed products
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2203/00—Foams characterized by the expanding agent
- C08J2203/06—CO2, N2 or noble gases
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2203/00—Foams characterized by the expanding agent
- C08J2203/08—Supercritical fluid
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
- C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
- C08J2323/10—Homopolymers or copolymers of propene
- C08J2323/14—Copolymers of propene
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2423/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
- C08J2423/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
- C08J2423/10—Homopolymers or copolymers of propene
- C08J2423/14—Copolymers of propene
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- Chemical & Material Sciences (AREA)
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- Chemical Kinetics & Catalysis (AREA)
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Abstract
The invention discloses a preparation method of a polypropylene foam material with controllable internal pressure, which comprises the following steps: 1) selecting high-melting-point random copolymerization polypropylene A and low-melting-point random copolymerization polypropylene B as raw materials; 2) adding an inorganic nucleating agent into the raw materials in the step 1) according to the proportion, and performing coextrusion granulation through an extrusion process to prepare a foaming master batch, wherein the random copolymerization polypropylene A is a core layer, and the random copolymerization polypropylene B is a skin layer; 3) putting the foaming master batch prepared in the step 2) into a reaction kettle to foam into polypropylene foaming beads; 4) pre-pressing the polypropylene foaming beads prepared in the step 3); 5) and (3) using the polypropylene expanded beads prepared in the step 4) for molding, calculating the internal pressure of the polypropylene expanded beads prepared in the step 4) through prepressing treatment, and adjusting the proportion of the random copolymer polypropylene A, the random copolymer polypropylene B and the inorganic nucleating agent according to the internal pressure value and the molding process conditions.
Description
The technical field is as follows:
the invention relates to the technical field of preparation of foaming polypropylene raw materials, in particular to a preparation method of a polypropylene foaming material with controllable internal pressure.
Background art:
the general procedure for molding expanded polypropylene (EPP) is as follows: firstly, pre-pressing the expanded polypropylene raw material beads, conveying the pre-pressed expanded polypropylene beads into a mold cavity, introducing high-temperature steam with certain pressure to expand and form the beads again, introducing cooling water to cool the product, opening the mold, enabling the product to fall off, and placing the product into a drying room for further drying and shaping. Compressed air with certain pressure is stored in the polypropylene foaming beads after pre-pressing treatment, which is generally called as the internal pressure of the beads, the internal pressure of the beads is crucial to molding, and when the internal pressure is insufficient, a workpiece is seriously shrunk, the size is difficult to control, and the appearance is easy to have defects so as to influence the apparent quality; when the internal pressure is higher, the forming needs higher steam pressure, and needs longer water-cooling time, not only causes the energy consumption extravagant, causes damage and shaping cycle extension to the mould, influences production efficiency, and when the internal pressure is higher, the forming needs higher steam temperature, and the foaming polypropylene finished piece very easily produces the curtain coating phenomenon under high temperature, and especially old mould is changeed and is appeared "overlap" at the finished piece edge, needs manual cutting, influences production efficiency and improves the cost of labor.
The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
The invention content is as follows:
the invention aims to provide a preparation method of a polypropylene foaming material with controllable internal pressure, thereby overcoming the defects in the prior art.
In order to achieve the aim, the invention provides a preparation method of a polypropylene foaming material with controllable internal pressure, which comprises the following steps:
1) selecting high-melting-point random copolymerization polypropylene A and low-melting-point random copolymerization polypropylene B as raw materials;
2) adding an inorganic nucleating agent into the raw materials in the step 1) according to the proportion, and performing co-extrusion granulation through an extrusion process to prepare a foaming master batch, wherein the random copolymerization polypropylene A is used as a foaming master batch core layer, and the random copolymerization polypropylene B is used as a foaming master batch skin layer;
3) putting the foaming master batch prepared in the step 2) into a reaction kettle, and foaming the foaming master batch into polypropylene foaming beads by using supercritical carbon dioxide as a foaming agent;
4) pre-pressing the polypropylene foaming beads prepared in the step 3);
5) and (3) using the polypropylene expanded beads subjected to the prepressing treatment in the step 4) for molding, calculating the internal pressure of the polypropylene expanded beads subjected to the prepressing treatment in the step 4), and adjusting the proportion of the random copolymer polypropylene A, the random copolymer polypropylene B and the inorganic nucleating agent according to the internal pressure value and the molding process conditions.
The melting point of the random copolymerization polypropylene A in the step 1) is 150-155 ℃, and the melt index is 2-3g/10 min; the melting point of the random copolymerization polypropylene B is 125-130 ℃, and the melt index is 7-9g/10 min.
The weight ratio of the random copolymerization polypropylene A to the random copolymerization polypropylene B in the step 1) is (10-95): (90-5).
The weight ratio of the random copolymerization polypropylene A to the random copolymerization polypropylene B in the step 1) is (80-95): (20-5).
The inorganic nucleating agent in the step 2) is one or a combination of more of talcum powder, calcium carbonate, silicon dioxide, zinc borate, titanium dioxide and aluminum oxide, the inorganic nucleating agent is of a random sheet structure and has the specification of 5-8 mu m, and the weight of the inorganic nucleating agent accounts for 3.5-5% of the total weight of the mixed material in the step 1).
The method for calculating the internal pressure of the polypropylene expanded beads in the step 5) is as follows:
1) preparing nylon mesh bag and balance, weighing the nylon mesh bag by the balance and recording as m1；
2) Putting a certain amount of foaming beads into the nylon mesh bag and sealing the nylon mesh bag;
3) putting the nylon mesh bag in the step 2) into a prepressing tank for prepressing treatment, and prepressing according to a preset prepressing program;
4) taking out the nylon mesh bag immediately after the pre-pressing is finished, weighing the nylon mesh bag, and recording the weight as m2；
5) Putting the nylon mesh bag weighed in the step 4) into an oven to bake for 2 hours until the weight of the mesh bag is constant, and recording the weight as m3；
6) Testing step 5) the bulk density ρ of the expanded beads in the mesh bag (see patent CN 206450547);
7) the internal pressure of the polypropylene expanded beads was calculated according to the following formula:
wherein the unit of P is bar, the unit of rho is g/L, m1、m2、m3The unit of (a) is g, T is the ambient temperature on the day of the test, and the temperature of the compressed air in the pre-pressing tank is the same as the ambient temperature.
Compared with the prior art, the invention has the following beneficial effects:
(1) the co-extruded materials of the two random copolymerization polypropylenes with high melting point and low melting point are used as foaming raw materials, the fusion bonding between the bead skin layers can be finished by adopting lower steam temperature in the molding process, and the temperature is not enough to enable the polypropylene with high melting point and low melting index of the core layer to flow greatly, so that the tape casting is avoided;
(2) the nucleating agent adopts an irregular sheet structure, and the specific shape and size ensure the cell structure and size of the expanded beads, so that the pressure can be quickly relieved even after the subsequent high-pressure prepressing treatment and the molding forming process, and the lower internal pressure is kept;
(3) the proportion of the two random copolymerization polypropylenes and the random sheet structure nucleating agent can be optimized by calculating the internal pressure of the expanded beads and combining with the molding process parameters of the expanded beads, thereby fundamentally solving the phenomenon of 'flash' at the edge of a workpiece and playing the roles of saving energy and reducing consumption.
Description of the drawings:
FIG. 1 is a graph showing the molding parameters and calculated values of the internal pressure of polypropylene expanded beads in examples 1 to 6 of the present invention.
The specific implementation mode is as follows:
the following detailed description of specific embodiments of the invention is provided, but it should be understood that the scope of the invention is not limited to the specific embodiments.
Throughout the specification and claims, unless explicitly stated otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element or component but not the exclusion of any other element or component.
Example 1:
a preparation method of a polypropylene foaming material with controllable internal pressure comprises the following steps:
1) selecting 95 parts by weight of high-melting-point random copolymer polypropylene A and 5 parts by weight of low-melting-point random copolymer polypropylene B as raw materials;
2) adding 3.5 parts of inorganic nucleating agent by the total amount of the step 1), and performing co-extrusion granulation by an extrusion process to prepare a foaming master batch, wherein the random copolymerization polypropylene A is used as a foaming master batch core layer, and the random copolymerization polypropylene B is used as a foaming master batch skin layer;
3) putting the foaming master batch prepared in the step 2) into a reaction kettle, and foaming the foaming master batch into polypropylene foaming beads by using supercritical carbon dioxide as a foaming agent;
4) pre-pressing the polypropylene foaming beads prepared in the step 3);
5) and (3) using the polypropylene expanded beads subjected to the prepressing treatment in the step 4) for molding, calculating the internal pressure of the polypropylene expanded beads subjected to the prepressing treatment in the step 4), and adjusting the proportion of the random copolymer polypropylene A, the random copolymer polypropylene B and the inorganic nucleating agent according to the internal pressure value and the molding process conditions.
The melting point of the random copolymerization polypropylene A in the step 1) is 150-155 ℃, and the melt index is 2-3g/10 min; the melting point of the random copolymerization polypropylene B is 125-130 ℃, and the melt index is 7-9g/10 min.
The inorganic nucleating agent in the step 2) is made of irregular flaky talcum powder with the specification of 6 mu m.
The foaming temperature in the reaction kettle in the step 3) is 155.6 ℃.
Example 2:
a preparation method of a polypropylene foaming material with controllable internal pressure comprises the following steps:
1) 93 parts of high-melting-point random copolymer polypropylene A and 7 parts of low-melting-point random copolymer polypropylene B are selected as raw materials in parts by weight;
2) adding 1.5 parts of inorganic nucleating agent by the total amount of the step 1), and performing co-extrusion granulation by an extrusion process to prepare a foaming master batch, wherein the random copolymerization polypropylene A is used as a foaming master batch core layer, and the random copolymerization polypropylene B is used as a foaming master batch skin layer;
3) putting the foaming master batch prepared in the step 2) into a reaction kettle, and foaming the foaming master batch into polypropylene foaming beads by using supercritical carbon dioxide as a foaming agent;
4) pre-pressing the polypropylene foaming beads prepared in the step 3);
5) and (3) using the polypropylene expanded beads subjected to the prepressing treatment in the step 4) for molding, calculating the internal pressure of the polypropylene expanded beads subjected to the prepressing treatment in the step 4), and adjusting the proportion of the random copolymer polypropylene A, the random copolymer polypropylene B and the inorganic nucleating agent according to the internal pressure value and the molding process conditions.
The melting point of the random copolymerization polypropylene A in the step 1) is 150-155 ℃, and the melt index is 2-3g/10 min; the melting point of the random copolymerization polypropylene B is 125-130 ℃, and the melt index is 7-9g/10 min.
The inorganic nucleating agent in the step 2) is made of irregular flaky silicon dioxide with the specification of 7 mu m.
The foaming temperature in the reaction kettle in the step 3) is 155.1 ℃.
Example 3:
a preparation method of a polypropylene foaming material with controllable internal pressure comprises the following steps:
1) selecting 94.5 parts by weight of high-melting-point random copolymerization polypropylene A and 5.5 parts by weight of low-melting-point random copolymerization polypropylene B as raw materials;
2) adding 3 parts of inorganic nucleating agent by the total amount of the step 1), and performing co-extrusion granulation by an extrusion process to prepare a foaming master batch, wherein the random copolymerization polypropylene A is used as a foaming master batch core layer, and the random copolymerization polypropylene B is used as a foaming master batch skin layer;
3) putting the foaming master batch prepared in the step 2) into a reaction kettle, and foaming the foaming master batch into polypropylene foaming beads by using supercritical carbon dioxide as a foaming agent;
4) pre-pressing the polypropylene foaming beads prepared in the step 3);
5) and (3) using the polypropylene expanded beads subjected to the prepressing treatment in the step 4) for molding, calculating the internal pressure of the polypropylene expanded beads subjected to the prepressing treatment in the step 4), and adjusting the proportion of the random copolymer polypropylene A, the random copolymer polypropylene B and the inorganic nucleating agent according to the internal pressure value and the molding process conditions.
The melting point of the random copolymerization polypropylene A in the step 1) is 150-155 ℃, and the melt index is 2-3g/10 min; the melting point of the random copolymerization polypropylene B is 125-130 ℃, and the melt index is 7-9g/10 min.
The inorganic nucleating agent in the step 2) is irregular flaky zinc borate, and the specification is 7 mu m.
The foaming temperature in the reaction kettle in the step 3) is 155.4 ℃.
Example 4:
a preparation method of a polypropylene foaming material with controllable internal pressure comprises the following steps:
1) selecting 91.5 parts by weight of high-melting-point random copolymer polypropylene A and 8.5 parts by weight of low-melting-point random copolymer polypropylene B as raw materials;
2) adding 5 parts of inorganic nucleating agent by the total amount of the step 1), and performing co-extrusion granulation by an extrusion process to prepare a foaming master batch, wherein the random copolymerization polypropylene A is used as a foaming master batch core layer, and the random copolymerization polypropylene B is used as a foaming master batch skin layer;
3) putting the foaming master batch prepared in the step 2) into a reaction kettle, and foaming the foaming master batch into polypropylene foaming beads by using supercritical carbon dioxide as a foaming agent;
4) pre-pressing the polypropylene foaming beads prepared in the step 3);
5) and (3) using the polypropylene expanded beads subjected to the prepressing treatment in the step 4) for molding, calculating the internal pressure of the polypropylene expanded beads subjected to the prepressing treatment in the step 4), and adjusting the proportion of the random copolymer polypropylene A, the random copolymer polypropylene B and the inorganic nucleating agent according to the internal pressure value and the molding process conditions.
The melting point of the random copolymerization polypropylene A in the step 1) is 150-155 ℃, and the melt index is 2-3g/10 min; the melting point of the random copolymerization polypropylene B is 125-130 ℃, and the melt index is 7-9g/10 min.
The inorganic nucleating agent in the step 2) is random flaky zinc borate, and the specification is 6 mu m.
The foaming temperature in the reaction kettle in the step 3) is 156.3 ℃.
Example 5:
a preparation method of a polypropylene foaming material with controllable internal pressure comprises the following steps:
1) 93.5 parts of high-melting-point random copolymerization polypropylene A and 6.5 parts of low-melting-point random copolymerization polypropylene B are selected as raw materials in parts by weight;
2) adding 2 parts of inorganic nucleating agent by the total amount of the step 1), and performing co-extrusion granulation by an extrusion process to prepare a foaming master batch, wherein the random copolymerization polypropylene A is used as a foaming master batch core layer, and the random copolymerization polypropylene B is used as a foaming master batch skin layer;
3) putting the foaming master batch prepared in the step 2) into a reaction kettle, and foaming the foaming master batch into polypropylene foaming beads by using supercritical carbon dioxide as a foaming agent;
4) pre-pressing the polypropylene foaming beads prepared in the step 3);
5) and (3) using the polypropylene expanded beads subjected to the prepressing treatment in the step 4) for molding, calculating the internal pressure of the polypropylene expanded beads subjected to the prepressing treatment in the step 4), and adjusting the proportion of the random copolymer polypropylene A, the random copolymer polypropylene B and the inorganic nucleating agent according to the internal pressure value and the molding process conditions.
The melting point of the random copolymerization polypropylene A in the step 1) is 150-155 ℃, and the melt index is 2-3g/10 min; the melting point of the random copolymerization polypropylene B is 125-130 ℃, and the melt index is 7-9g/10 min.
The inorganic nucleating agent in the step 2) is irregular flaky calcium carbonate with the specification of 8 mu m.
The foaming temperature in the reaction kettle in the step 3) is 155.3 ℃.
Example 6:
a preparation method of a polypropylene foaming material with controllable internal pressure comprises the following steps:
1) selecting 96 parts by weight of high-melting-point random copolymer polypropylene A and 4 parts by weight of low-melting-point random copolymer polypropylene B as raw materials;
2) adding 3.5 parts of inorganic nucleating agent by the total amount of the step 1), and performing co-extrusion granulation by an extrusion process to prepare a foaming master batch, wherein the random copolymerization polypropylene A is used as a foaming master batch core layer, and the random copolymerization polypropylene B is used as a foaming master batch skin layer;
3) putting the foaming master batch prepared in the step 2) into a reaction kettle, and foaming the foaming master batch into polypropylene foaming beads by using supercritical carbon dioxide as a foaming agent;
4) pre-pressing the polypropylene foaming beads prepared in the step 3);
5) and (3) using the polypropylene expanded beads subjected to the prepressing treatment in the step 4) for molding, calculating the internal pressure of the polypropylene expanded beads subjected to the prepressing treatment in the step 4), and adjusting the proportion of the random copolymer polypropylene A, the random copolymer polypropylene B and the inorganic nucleating agent according to the internal pressure value and the molding process conditions.
The melting point of the random copolymerization polypropylene A in the step 1) is 150-155 ℃, and the melt index is 2-3g/10 min; the melting point of the random copolymerization polypropylene B is 125-130 ℃, and the melt index is 7-9g/10 min.
The inorganic nucleating agent in the step 2) is random flaky zinc borate, the specification is 6 mu m, and the foaming temperature is 155.7 ℃.
The foaming temperature in the reaction kettle in the step 3) is 155.7 ℃.
The internal pressure of the polypropylene expanded beads prepared in examples 1 to 6 was calculated by the following specific calculation method:
1) preparing nylon mesh bag and balance, weighing the nylon mesh bag by the balance and recording as m1；
2) Putting a certain amount of foaming beads into the nylon mesh bag and sealing the nylon mesh bag;
3) putting the nylon mesh bag in the step 2) into a prepressing tank for prepressing treatment, and prepressing according to a preset prepressing program;
4) taking out the nylon mesh bag immediately after the pre-pressing is finished, weighing the nylon mesh bag, and recording the weight as m2；
5) Putting the nylon mesh bag weighed in the step 4) into an oven to bake for 2 hours until the weight of the mesh bag is constant, and recording the weight as m3；
6) Testing step 5) the bulk density ρ of the expanded beads in the mesh bag (see patent CN 206450547);
7) the internal pressure of the polypropylene expanded beads was calculated according to the following formula:
wherein the unit of P is bar, the unit of rho is g/L, m1、m2、m3The unit of (a) is g, T is the ambient temperature on the day of the test, and the temperature of the compressed air in the pre-pressing tank is the same as the ambient temperature.
For example, the following steps are carried out: if the environmental temperature T =20.3 ℃ on the test day, m1=20.45g，m2=48.60g，m3=26.93g, ρ =19.2g/L, then P =1.42bar, wherein the procedure for the pre-pressure foaming treatment in step 3) is as follows: the pressure in the pre-pressing tank is increased from 0 bar to 5 bar, and the time is 12 h; reducing the pressure from 5 bar to 3 bar for 1 h; the pressure was then maintained at 3 bar for 1 h.
The parameters of the molding process and the calculated values of the internal pressure of the polypropylene expanded beads in the above examples 1 to 6 are shown in FIG. 1.
From the experimental results, under the mixture ratio of 91.5 parts of high-melting-point random copolymer polypropylene A, 8.5 parts of low-melting-point random copolymer polypropylene B and 5 parts of inorganic nucleating agent, the internal pressure of the polypropylene foaming beads is low, the required forming pressure is relatively low, the subsequent forming water cooling period can be reduced, the energy consumption is saved, and the problem of 'flash' can be solved fundamentally.
The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable one skilled in the art to make and use various exemplary embodiments of the invention and various alternatives and modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims and their equivalents.
Claims (6)
1. The preparation method of the polypropylene foaming material with controllable internal pressure is characterized by comprising the following steps:
1) selecting high-melting-point random copolymerization polypropylene A and low-melting-point random copolymerization polypropylene B as raw materials;
2) adding an inorganic nucleating agent into the raw materials in the step 1) according to the proportion, and performing co-extrusion granulation through an extrusion process to prepare a foaming master batch, wherein the random copolymerization polypropylene A is used as a foaming master batch core layer, and the random copolymerization polypropylene B is used as a foaming master batch skin layer;
3) putting the foaming master batch prepared in the step 2) into a reaction kettle, and foaming the foaming master batch into polypropylene foaming beads by using supercritical carbon dioxide as a foaming agent;
4) pre-pressing the polypropylene foaming beads prepared in the step 3);
5) and (3) using the polypropylene expanded beads subjected to the prepressing treatment in the step 4) for molding, calculating the internal pressure of the polypropylene expanded beads subjected to the prepressing treatment in the step 4), and adjusting the proportion of the random copolymer polypropylene A, the random copolymer polypropylene B and the inorganic nucleating agent according to the internal pressure value and the molding process conditions.
2. The method as claimed in claim 1, wherein the melting point of the random copolymer polypropylene A in step 1) is 150-155 ℃ and the melt index is 2-3g/10 min; the melting point of the random copolymerization polypropylene B is 125-130 ℃, and the melt index is 7-9g/10 min.
3. The method for preparing polypropylene foam material with controllable internal pressure according to claim 1, wherein the weight ratio of the random copolymerized polypropylene A and the random copolymerized polypropylene B in the step 1) is (10-95): (90-5).
4. The method for preparing polypropylene foam material with controllable internal pressure according to claim 1, wherein the weight ratio of the random copolymerized polypropylene A and the random copolymerized polypropylene B in the step 1) is (80-95): (20-5).
5. The method for preparing the polypropylene foam material with controllable internal pressure according to claim 1, wherein the inorganic nucleating agent in the step 2) is one or more of talcum powder, calcium carbonate, silicon dioxide, zinc borate, titanium dioxide and aluminum oxide, the inorganic nucleating agent has a random sheet structure and a specification of 5-8 μm, and the weight of the inorganic nucleating agent accounts for 3.5-5% of the total weight of the raw materials in the step 1).
6. The method for preparing a polypropylene foam material with controllable internal pressure according to claim 1, wherein the internal pressure of the polypropylene foam beads in the step 5) is calculated by the following method:
1) preparing nylon mesh bag and balance, weighing the nylon mesh bag by the balance and recording as m1；
2) Putting a certain amount of foaming beads into the nylon mesh bag and sealing the nylon mesh bag;
3) putting the nylon mesh bag in the step 2) into a prepressing tank for prepressing treatment, and prepressing according to a preset prepressing program;
4) taking out the nylon mesh bag immediately after the pre-pressing is finished, weighing the nylon mesh bag, and recording the weight as m2；
5) Putting the nylon mesh bag weighed in the step 4) into an oven to bake for 2 hours until the weight of the mesh bag is constant, and recording the weight as m3；
6) Testing the bulk density rho of the expanded beads in the mesh bag in the step 5);
7) the internal pressure of the polypropylene expanded beads was calculated according to the following formula:
wherein the unit of P is bar, the unit of rho is g/L, m1、m2、m3The unit of (a) is g, T is the ambient temperature on the day of the test, and the temperature of the compressed air in the pre-pressing tank is the same as the ambient temperature.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109883604A (en) * | 2019-02-19 | 2019-06-14 | 无锡会通轻质材料股份有限公司 | A kind of polymer foaming bead internal pressure evaluation method |
| CN110229372A (en) * | 2019-05-24 | 2019-09-13 | 天津市大林新材料科技股份有限公司 | Low molding energy consumption polypropylene foamed particles of one kind and preparation method thereof |
| CN112457596A (en) * | 2019-11-21 | 2021-03-09 | 无锡会通轻质材料股份有限公司 | Energy-saving expanded polypropylene beads and preparation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109883604A (en) * | 2019-02-19 | 2019-06-14 | 无锡会通轻质材料股份有限公司 | A kind of polymer foaming bead internal pressure evaluation method |
| CN110229372A (en) * | 2019-05-24 | 2019-09-13 | 天津市大林新材料科技股份有限公司 | Low molding energy consumption polypropylene foamed particles of one kind and preparation method thereof |
| CN112457596A (en) * | 2019-11-21 | 2021-03-09 | 无锡会通轻质材料股份有限公司 | Energy-saving expanded polypropylene beads and preparation method thereof |
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